The invention relates to a method of semiconductor manufacturing process, and more particularly to a method of forming a silicon tip by a single etching process, which can be used to form a tip floating gate to increase erase speed.
Flash memory, which has the advantages of nonvolatility, high density, low power consumption, and low cost, has become a major product of the semiconductor industry.
Flash memory, which comprises a control gate used to apply operating voltage and a floating gate used to store charges, performs program or erase operations by applying different voltages of the control gate, source, and drain to move charges on and off the floating gate.
When the edge of the floating gate is a tip, the electrical field is easily concentrated, and the point is easily discharged. If the point discharge is increased, the erasing effect is strong.
U.S. Pat. No. 6,759,300 discloses a method for fabricating a multi-tip floating gate by an anisotropic etching process with gases comprising CF4, CHF3, or a combination thereof, and the tip angle can be controlled by the angle of the anisotropic etching process.